ISRIB Side Effects

Reported ISRIB side effects

There is no human safety record ISRIB has never been given to people in a registered study, so no human adverse event, laboratory, dosing or interaction data exist. Everything below comes from animals or cells. What animal studies recorded The original paper reported no overt toxicity in mice at the doses used (PMID: 23741617). In prion-infected mice, daily ISRIB at 0.25 mg/kg for about five weeks left the pancreas intact, with normal pancreatic weight and preserved exocrine and endocrine structure and no change in blood glucose, while the PERK kinase inhibitor GSK2606414 roughly halved pancreatic weight and raised blood glucose in the same model. The ISRIB-treated animals still had to be killed at about 96 days for losing 20 percent of body weight, which the authors could not explain by pancreatic damage or diabetes and attributed either to off-target effects or to the consequences of prolonged prion infection in animals that survived longer (PMID: 25741597). A mortality signal in one transgenic line A study at Stanford gave 5 mg/kg of ISRIB once daily to several mouse lines. C57BL/6J mice tolerated 62 consecutive days of that dose, and PS19 tau mice received it for nine weeks. In the APP amyloid line, daily dosing was stopped on day 8 because of a significant increase in mortality in the treated animals; seven APP mice died during the second week of treatment, four non-transgenic and three transgenic, all of them in ISRIB groups. The protocol was then changed to dosing only on behavioural test days at 0.25 or 2.5 mg/kg (PMID: 28721361). This is the clearest adverse finding in the published ISRIB literature. Mechanism-based reasons for caution The integrated stress response is protective as well as harmful. ISRIB reduced the viability of cells placed under chronic endoplasmic reticulum stress by PERK activation (PMID: 23741617). In cancer models the same action has been used deliberately: in patient-derived models of aggressive prostate cancer, ISRIB was cytotoxic to metastatic tumour cells that depend on the stress response (PMID: 29720449), and in breast cancer cells ISRIB combined with bortezomib pushed cells into a form of cell death by restoring translation (PMID: 35114585). In cultured cells carrying a mutant tRNA that causes mistranslation, the cells became resistant to ISRIB and slower to clear protein aggregates (PMID: 34718744). Gaps No published study reports human pharmacokinetics, a tolerated dose, long-term safety, reproductive safety or drug interactions for ISRIB. The animal work uses injections, not oral dosing, and the compound's poor solubility is the published reason it was not developed further (PMID: 42153306).

When to continue, reduce, or stop ISRIB

ISRIB contraindications

No human data at all. ISRIB has not been given to people in any registered study, so there is no basis for describing how a person would respond to it (ClinicalTrials.gov search, 25 October 2026). Conditions where the stress response is protective. ISRIB reduced the viability of cells under sustained endoplasmic reticulum stress (PMID: 23741617), and blocking the response is deliberately cytotoxic in some tumour models (PMID: 29720449, PMID: 35114585). A compound that removes a protective brake on protein synthesis is not neutral in a cell that needs that brake. Mice of an APP amyloid line died on daily dosing. Daily ISRIB at 5 mg/kg had to be stopped after eight days in an APP amyloid cohort because of a significant rise in mortality, and four of the seven deaths were in non-transgenic mice of that line. The same dose did not do this in C57BL/6J or PS19 mice (PMID: 28721361). Acute, strong stress states. ISRIB cannot suppress the integrated stress response once phosphorylated eIF2 passes a threshold, so its effects depend on how strongly the pathway is switched on (PMID: 30674674, PMID: 33220178). Not a medicine. ISRIB is a research chemical with no approval anywhere and no clinical indication.

Why vendor quality drives ISRIB side-effect frequency

Research-compound communities consistently report that adverse-event frequency tracks with source quality. Three reasons: (1) impurity profiles vary by lab (residual synthesis byproducts can trigger reactions); (2) mislabeled mass means actual dose can be 50-150% of stated dose; (3) reconstitution-grade water and capping methodology affect long-term storage stability. COA-verified vendors with published HPLC data minimize all three failure modes. Check a vendor's COA record and Trust Score before you buy.

ISRIB side effects FAQ

Research-use disclaimer. All safety information on this page summarizes published research literature and community-reported reactions. It is not medical advice and not authorization for human consumption. Always consult a licensed practitioner before any compound enters a clinical context. Compounds linked from this page are sold for research-use only.
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